In GS mains exam, direct questions are usually asked from the book (NCERT, Goh Cheng Leong). This is an important topic from NCERT and is related to GS-1 syllabus- Salient features of world’s physical geography.

And, Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc., geographical features and their location

Key demand of the question

This is a straightforward question which wants us to explain the role of seismology in understanding the interior structure of the earth.

Directive word

Explain- we have to write in detail about how seismology helps us in studying the interior structure of the Earth. In geography questions, we also have to draw a diagram to our explanation.

Structure of the answer

Introduction- mention that the structure of Earth’s deep interior cannot be studied directly but geologists use seismic (earthquake) waves to understand the interior structure of earth.

Body-

define what are seismic waves and their types.

Explain how the difference in their properties helps us to understand the earth’s interior. Also draw a diagram for better presentation of your answer.

Conclusion – mention other methods to study the earth’s interior structure. e.g observations of rock in outcrop, samples brought to the surface from greater depths by volcanic activity, measurements of the gravitational and magnetic fields of the Earth, and experiments with crystalline solids at pressures and temperatures characteristic of the Earth’s deep interior.